The robot tricks to bridge the uncanny valley

Giving robots a series of small behavioural tics can make help them appear a lot more human, which makes us feel more comfortable interacting with them

Could the ROBOY be more human?

(Image: Erik Tham/Corbis)

IF A robot bleeped and squeaked with personality like R2D2 from Star Wars, would you like it better? What if it glanced into the distance when you asked it a question, as though pondering its response?

Little behavioural tics like these could be crucial to people accepting robots into their everyday lives. Though they may seem small, such tweaks can help bridge the “uncanny valley”, making the difference between a robot that looks eerily unhuman and one that people can easily relate to and work with.

To test the idea, Robin Read at Plymouth University in the UK has been imbuing robots with sounds that might elicit an emotional response from people.

Read and colleague Tony Belpaeme created two sounds&colon; a chirpy, positive-sounding bleep and a melancholy whine. They then recorded footage of a humanoid robot – the Nao from Aldebaran Robotics of Paris, France – making each sound after being slapped, kissed, stroked or having its eyes covered. Then 300 people on the crowdsourcing website CrowdFlower were asked to rate how they perceived the robot’s feelings after each action.

In general, people had a similar response to each sound. But the pair found that people were more engaged when the robot made a sound than when it didn’t.

“It is enough to choose or generate a random sound,” Read says, as that’s all that’s needed to inform someone that something important is going on. “It seems to be an easy way to provide rich expression for robots,” he says. The findings were presented at the Human-Robot Interaction conference in Bielefeld, Germany, on 3 March.

“Giving robots the ability to make sounds is an easy way to provide them with rich expressions”

Sean Andrist at the University of Wisconsin-Madison and his team have a number of other tricks to make a humanoid robot seem “alive”. One is to introduce small random movements into a robot’s head rotation motor, so that instead of appearing stationary, the robot’s head twitches slightly now and then.

A face-tracking camera can ensure a robot always looks at the person it is interacting with, but instead of staring straight at their face, the team have programmed in a tendency for the robot to avert its gaze from time to time. The idea is to mimic the human habit of glancing fleetingly to one side when thinking of an answer to a question.

The team asked 30 students to assess conversations with Nao robots programmed to act like librarians or job interviewers, some of which had been set up for gaze aversion. They found that people thought robots that glanced around seemed more purposeful and thoughtful. The glances also led to fewer inappropriate interruptions in a conversation with the robot, Andrist says.

Gaze plays another key role. Using a PR2 humanoid robot, Ajung Moon at the University of British Columbia in Vancouver, Canada, found that for people to feel comfortable when a robot hands them an object, it is crucial that they lock gaze first. Then the robot must look to the point in space where it plans to make the handover.

This can be improved further, says Anca Dragan of Carnegie Mellon University in Pittsburgh. She has been carrying out tests with a humanoid robot called Herb and has experimented with introducing a small delay to the robot-human handover. Just a few tenths of a second was enough to mimic a natural human hesitation, even if it made the overall handover feel less smooth.

It may seem less efficient, but people take to these small differences in robot behaviour, says Dragan. “Such handover motions have to match human expectations,” she says. “You don’t want the robot moving in ways that surprise or shock people.”